1. Field of the Invention
The present field of the invention is related to a wafer container, and more particularly, to a latch component disposed in door of wafer container.
2. Description of the Prior Art
The semiconductor wafers are transferred to different stations to apply the various processes in the required equipments. A sealed container is provided for automatic transfer to prevent the pollution from occurring during transferring process. FIG. 1 shows the views of wafer container of the conventional prior art. The wafer container is a front opening unified pod (FOUP) which includes a container body 10 and a door 20. The container body 10 is disposed with a plurality of slots 11 for horizontally supporting a plurality of wafers, and an opening 12 is located on a sidewall of the container body 10 for importing and exporting. Further, the door 20 includes an outer surface 21 and an inner surface 22, in which the door 20 is joined with the opening 12 of the container body 10 via inner surface 22 to protect the plurality of wafers within the container body 10. Furthermore, at least one latch hole 23 is disposed on the outer surface 21 of the door 20 for opening or closing the wafer container. According to the aforementioned, due to that wafers are placed in the container body 10 horizontally, thus, the FOUP needs a wafer restraint component to prevent the wafer from displacement or from movement toward the opening 12 of container body 10 occurring during the wafer transportation due to vibration.
FIG. 2 is a view of a front opening unified pod (FOUP) as described in U.S. Pat. No. 6,736,268. As shown in FIG. 2, the inner surface 22 of the door 20 is disposed with a recess 24 and the recess 24 is extended from the top 221 of the inner surface 22 to the bottom 222, and is located between two latch components 230 (inside of the door 20). A wafer restraint module (not shown in Figure) is further disposed in the recess 24. The wafer restraint module consists two wafer restraint components 100, and each wafer restraint component 100 includes a plurality of wafer contact heads 110 to sustain corresponding wafers, so as to prevent the wafer from displacement or movement toward the door opening due to vibration occurring in the wafer transportation procedure. However, the above-mentioned wafer restraint module is disposed on the recess 24 of the inner surface 22 of the door 20, and the wafer is merely attached to the inner surface 22 of the door 20 or the wafer is partially settled down within the recess 24. The wafers either sit adjacent to the inner surface 22 of the door 20 or only slightly enter into the recess 24. As a result, the wafers are not securely and fully settled into the recess 24 and the length between the front side and the back side of the FOUP is not effectively shortened. In addition, the tiny dust particles generated due to the friction between the wafer restraint module and the wafers can be easily accumulated in the recess 24. In the process of cleaning the accumulated dust particles, it is necessary to separate the wafer restraint module from the recess 24 on the inner surface 22 of the door 20. By frequent separation and assembly of the wafer restraint module in order to apply the cleaning process, the wafer restraint module is easily slackened.
Furthermore, FIG. 3 is a view of latch component 230 in door 20 of a front opening unified pod (FOUP) as described in U.S. Pat. No. 5,711,427. The method for assembling the door 20 and container body 10 is mainly to dispose a movable bolts 231 on the two sides of door 20 (namely between outer surface 21 and inner surface 22) and to dispose socket holes (not shown in Figure) adjacent to the edge of opening of door 10 and corresponding to bolts 231. The objective of fixing the door 20 in the container body 10 can thus be achieved with the turning of latch hole disposed on outer surface 21 of door 20 and the inserting of latch bolts 231 into socket holes, in which the insertion and withdrawal of latch bolts 231 are controlled by the turning of latch hole via a round-shaped cam 232.
And in the operating practice of semiconductor factory, the opening of FOUP is mainly operated through a wafer carrying apparatus (not shown in Figure). The wafer carrying apparatus includes at least one opening latch (not shown in Figure) that is to be inserted into the latch hole 23 on outer surface 21 of door 20 of the FOUP and to turn cam 232 to drive the movable bolts 231 to open or close the FOUP.
In addition, other U.S. patents that describe latch component in door of FOUP include U.S. Pat. Nos. 5,915,562, 5,957,292, 6,622,883, and 6,902,063. In order to achieve air tightness when joining door and container body, movable bolts will shift longitudinally for fastening a springy air-tight component, which leads to achievement of both objectives of closing FOUP and air tightness. However, in prior latch patents, complex mechanic apparatuses are used, the usage of which not only results in higher failure rate but also generates too much mechanical friction in the operating process that pollutes wafers. Moreover, the air tightness achieved by fastening springy air-tight component with shift of movable bolts cannot sustain for very long time and is not effective enough.
Moreover, in conventional FOUP, some restraint components are disposed on the inner surface of door 20. Thus, when door 20 closes container body 10, the restraint components contact wafers and completely fix the wafers in order to prevent displacement of wafers in FOUP from happening during transportation procedure. And in order to avoid too forcible collision or friction between restraint components and wafers when contacting, therefore, as shown in FIG. 4, a few U.S. patents disclose springy component 86 that is disposed between cam 232 in latch component 230 and door 20. In the process in which cam 232 turns and drives movable bolts 231 to close FOUP, this springy component 86 can function as damping for restraint component disposed on inner surface of door 20 to contact wafers under mitigated and smooth condition, and thus the problem of collision and friction can be solved. These U.S. patents include U.S. Pat. Nos. 6,880,718, 7,168,587, and 7,182,203. However, in this way of laterally driving, it is easy for an offsetting force to generate on the moving direction of movable bolts 231 and cause failure of insertion of movable bolts into socket holes of container body 10. Thus, container body 10 and door 20 cannot be closed, and the production cost of FOUP is also increased.